Journal of Ceramic Processing Research. Vol. 17, No. 11, pp. 1155~1163 (2016)
1155
J O U R N A L O F
CeramicProcessing Research
Evaluation of the feasibility of using calcium aluminate composite (CAC) and
Acement as additives for regulated set cement
Ja-Sul Kooa, Seung-Yeup Yooa, Jin-Man Kimb,*, Sun-Mi Choib, Sang-Yoon Ohc and Dongyeop Hand
aTechnical Research Center, Tongyang Cement & Energy Corp., Samcheok, KoreabDept. of Architectural Engineering, Kongju National University, Cheonan, Chungnam, KoreacEcomaister Co. LTD, Incheon, KoreadDepartment of Architectural Engineering, and Engineering Research Institute, Gyeongsang National University, Jinju, Korea
This work aims to evaluate the feasibility of using calcium aluminate composite (CAC) manufactured from steel slag, quicklycooled with high pressure air, and Acement, produced from CAC and various additives including gypsum as enhancementsfor regulated set cement. To evaluate the performance CAC or Acement as the additives of regulated set cements, CAC andAcement were replaced for the commercially available calcium sulfoaluminate cement (CSA)-based rapid setting cement(RSC). The engineering properties of workability, strength, and elastic modulus of mortar and concrete phases were thentested. From the mortar tests, as the replacement ratio of CAC was increased, the compressive strength of the mortarsignificantly decreased because of reduced amounts of gypsum for ettringite formation. On the other hand, as the replacementratio of Acement including gypsum was increased, the compressive strength increased due to enhanced ettringite formation.From the test results, Acement displayed more favorable results as an additive for the rapid setting cement than CAC. CACcontinued to show good performance at less than 10% of replacement ratio. Concrete testing revealed that mechanicalperformances of compressive, tensile, and flexural strength and elastic modulus all improved by 10% with CAC replacementand by 20% with Acement replacement. However, the resistivity performances for freeze-thaw tests and carbonation slightlydecreased.
Key words: Ultra-rapid setting cement, Rapidly-cooled steel slag, CAC, Acement.
Introduction
In the cement and concrete industry, many researchers
[1-3] advocate recycling various byproducts to
improve industrial competitiveness and sustainability, thus
developing “green technology.” According to the statistics
of the Korean Steel Association [4], the production of steel
products is increasing; hence the amount of steel slag, a
byproduct from the manufacturing process of steel
products, is also increasing. Hence, the demand for research
on the reutilization of steel manufacturing byproducts is
increasing.
Steel slag is categorized as either converter slag or
electric arc furnace slag. Additionally, electric arc
furnace slag is categorized as either ladle furnace slag or
oxidizing slag [5]. In South Korea, most steel slags are
dumped in the cooling yard without any distribution or
water-based aging treatment. Finally, these steel slags
have only been used as low valued material, such as for
filler aggregate.
One of the most critical reasons for limited recycling of
steel slag is the nature of expansion caused by free lime
(free-CaO; hereafter referred to as f-CaO). According to
previous research [6], by utilizing rapid-cooling
methods using high pressured air, it was possible to
produce steel slag with a hard glassy surface, which can
inhibit elution of f-CaO. Furthermore, it was reported
that ladle furnace slag produced with this method
contains Belite (β-C2S) and Mayenite (C12A7)1 so it was
possible to apply it as an additive or supplementary
material for cement-based materials [7, 8].
Therefore, in this research, the mortar and concrete
were prepared with a mixture of commercially available
CSA type rapid setting cement, and newly produced
rapid setting cement (Acement) using CaO-Al2O3
composites (hereafter referred to as CAC) produced by
quick cooling of molten ladle furnace slag by high-
pressured air. Using the mortar phase, the optimum ratio
of CAC or Acement is identified by fundamental tests
of fresh state and hardened states. Based on the
optimum ratio obtained from the mortar experiment,
various engineering properties in the concrete phase
were evaluated.
Theoretical Background
Occurrence of ladle furnace slag and stabilizationThe electric arc furnace process has several
functions: 1) Oxidation removes impurities such as Si,
Mn, Cr, and P by the oxidizing reaction of the solvent.
*Corresponding author: Tel : +82-41-521-9332E-mail: [email protected]
1156 Ja-Sul Koo, Seung-Yeup Yoo, Jin-Man Kim, Sun-Mi Choi, Sang-Yoon Oh and Dongyeop Han
2) The ladle process controls the chemical composition of
molten irons by stabilizing the temperature, introducing a
deoxidizer and ferro alloy, controlling the shape of non-
metallic inclusions, and removing impurities, such as P, S
(SiO2), C, (CaO), N, and H (H2O or OH). The slags
occurring in this ladle process represent approximately
15% of all electric arc furnace slag.
The f-CaO, normally existing in ladle furnace slag,
results from the incomplete reaction of quicklime with
other impurities during the refining process. Since the
f-CaO in the ladle furnace slag is a major cause of poor
volume stability, a stabilizing treatment is essential
before using this slag as a construction material. There
are some methods of aging, which stimulate reaction of
f-CaO with moisture by long-term exposure outdoors,
producing a hard glassy surface on slag. The most
common methods of stabilizing steel slag are spraying
high-pressured air or water on the molten material.
This reaction produces f-CaO as a stable phase by
adding additives and oxygen to the molten slag [9, 10].
Chemical compositions and constituent minerals ofrapidly cooled ladle furnace slag
Because of the large amount of flux used to remove
impurities of P, S, C, N, and H in molten iron during
the ladle furnace process, ladle furnace slag has high
concentrations of CaO, Al2O3, and SiO2. By rapidly
cooling this ladle furnace slag with high-pressure air,
most slag turns amorphous as shown in Fig. 1 of the
XRD analysis results. Since the amorphous compound
in ladle furnace slag is to evaluate the compounds, the
sample was re-calcined at 900 oC and slowly cooled
down for XRD analysis. From the compound of ladle
furnace slag, C12A7, and β-C2S were detected. On the
other hand, the f-CaO is removed by immediate
cooling in the reaction of CaO with Al2O3, and SiO2
[11]. For crystalized compounds, C12A7 produces the
hydration product of CAH10 at ordinary temperature
[12], but thermodynamically converts it to C3AH6, a
metastable hydration product through C3AH8. [13], and
this process of producing a metastable intermediate
hydration product causes low strength [14]; hence,
gypsum should be added to produce ettringite [15] and
monosulfate as shown in Equation (1), thereby delaying
the hydration speed and achieving stable and improved
strength [16] of the mixture. Additionally, β-C2S, the
same compound found in Portland cement, dominates
the long-term strength development [17].
C12A7 + 12CaSO4 + 137H2O →
4(C3A • 3CaSO4 • 32H2O) + 6AH3 (1)
Experimental
Material propertiesThe mortar experimental plan for identifying optimum
replacement ratio of CAC or Acement is shown in Table 1.
Based on the control mixture with RSC from “S”
company, the water-to-binder ratio was fixed at 0.40
with a cement-to-sand ratio of 1 to 3. The target mini
slump was designated as 110 ± 12.5 mm. For the
mortar experiment, the RSC from a single company (S
company) was used. The replacement ratios of CAC or
Fig. 1. XRD pattern of ladle furnace slag.
Table 1. Experiment plan for mortar.
Mixtures
W/B* 0.40
C : S** 1 : 3
Binder (plain)CSA***-based
regulated set cement(RSC from “S” company)
Additive CAC or Acement
Replacement ratio(% by binder weight)
0, 10, 20, 30
Tests
Fresh mortarTemperatureMini slump
Hardened mortarCompressive strength (3 h, 1, 3, 7, 14, 28D)
*W/B: water-to-binder ratio.**C: cement, S: sand.***CSA: Calcium sulfoaluminate (one of the most representa-tive types of regulated set cement).
Table 2. Mixing proportion of mortars.
ID* C:S** W/B***Unit weight (kg/m3)****
W RSC CAC Ace AD Re S
Plain
1 : 3 0.40 180
450 − − - 0.9
1350
C10 405 45 − 0.45 1.5
C20 360 90 − 0.90 2.1
C30 315 135 − 1.35 2.7
A10 405 − 45 1.6 1.6
A20 360 − 90 2.3 2.3
A30 315 − 135 3.1 3.1
*C10: CAC 10 wt. % replacement, A10: Acement 10 wt.%replacement.**C:S: cement : sand.***W/B: water-to-binder ratio.****W: water, RSC: commercially available rapid setting cement,Ace: Acement, AD: admixture (superplasticizer), Re: gypsum asa retarder, S: sand.
Evaluation of the feasibility of using calcium aluminate composite (CAC) and Acement as additives for regulated set cement 1157
Acement were prepared at 0, 10, 20, and 30% for four
different conditions. The temperature and mini-slump
were measured for fresh state mortar. For hardened
properties, compressive strength was measured every
three hours on days 1, 3, 7, 14, and 28. The mixing
proportions of mortars with various replacement ratios
of CAC or Acement are summarized in Table 2.
The experimental plan for concrete incorporating
CAC or Acement is summarized in Table 3, which
shows two different rapid setting cements from
different companies with a water-to-binder ratio fixed
to 0.40. The mix design was conducted to satisfy a 210
± 25 mm target slump and 4.5 ± 1.5% target air
content. Based on this design, CAC 10% or Acement
20% by weight was substituted for rapid setting
cement. Both CAC and Acement underwent the same
tests at different composition percentages. Six batches
were prepared from different companies (S & U): Plain
cement mixes are identified as S-RSC & U-RSC;
Acement mixes are SA20 and UA20; CAC mixes are
S-C10 and U-C10. Fresh state property measurements
were based on discharging temperatures recorded right
after the mixing process as well as slump and air
content. Hardened property measurements were based
on compressive strength, tensile strength, flexural
strength, elastic modulus, and autogenous deformation.
The compressive strength of the concrete was measured
at three hours and 1, 3, 7, 14, and 28 days. Special
attention was given to evaluate early age compressive
strength development at 3-hours, 1-day, and 3-day. For
other mechanical properties, the tests were conducted in
28 days. Freeze-thaw and carbonation resistivity tests
were used to evaluate durability performance. Table 4
shows the mixing proportions for each concrete mixture.
Sample preparationIn this research, rapid setting cements used were
obtained from two different sources, that is, the “S”
and “U” companies in South Korea. For the mortar
properties experiment, RSC from “S” company was
used. For the concrete properties experiment, RSC
from both “S” and “U” companies were used and
compared. For the RSC using CAC and Acement
additives, CAC was produced by crushing the rapidly
cooled ladle furnace slag, while Acement was
produced by adding gypsum and other additives as
setting time controllers in CAC. Table 5 shows the
material components for manufacturing Acement. Each
binder’s physical properties provided by manufacturer
and chemical compositions obtained by XRF are
shown in Table 6.
The aggregate used in the mortar experiment was
ISO standard sand obtained from South Korea. For the
concrete experiment, the fine aggregate was natural
river sand obtained from Kangwon-do, South Korea.
Coarse aggregate was the 25 mm grade crushed
Table 4. Mixing proportions of concrete.
ID* W/C** S/a***Unit weight**** (kg/m3)
W RSC CAC Ace S G AD AE Re
S-RSC
0.40 0.50 160
400 − − 861 881
4 0.12 0.8
S-C10 360 40 − 862 881
S-A20 320 − 80 861 880
U-RSC 400 − − 863 882
U-C10 360 40 − 863 882
U-A20 320 - 80 862 881
*S-RSC: “S” company rapid setting cement, S-C10: “S” company rapid setting cement based CAC 10% replacement, U-A20: “A” com-pany rapid setting cement based Acement 20% replacement.**W/C: water-to-cement ratio.***S/a: Sand-to-aggregate ratio.****W: water, RSC: rapid setting cement, Ace: Acement, S: sand, G: gravel, AD: admixture (superplasticizer), AE: air entrainer, and Re:gypsum as a retarder.
Table 3. Experiment plan for concrete.
Mixture
Unit water (kg/m3) 160
Unit cement (kg/m3) 400
Plain binder
RSC* from “S” company
RSC* from “U” com-pany
Additives replacement
CAC 10 wt. %Acement 20 wt. %
Tests
Fresh concrete
● Slump● Air content● Discharged temperature
Hardened concrete
Mechanical properties
● Compressive strength (3H, 1, 3, 7, 14, and 28 D)● Tensile strength (28 D)● Flexural strength (28 D)● Elastic modulus (28 D)● Autogenous shrinkage
Durability● Freeze-thaw resistivity● Carbonation depth
*RSC: rapid setting cement.
1158 Ja-Sul Koo, Seung-Yeup Yoo, Jin-Man Kim, Sun-Mi Choi, Sang-Yoon Oh and Dongyeop Han
aggregate from South Korea. The physical properties
of the aggregates used in the concrete experiment are
shown in Table 6 [18].
The water reducer used was a naphthalene-based
powder type water reducer from “K” company in
South Korea. To prevent rapid setting during the
mixing process, a dose of retarder was added. The
retarder used was a commercially available product in
South Korea. The physical properties of chemical
admixtures are shown in Table 7.
The mortar was mixed with a planetary mixer. The
mixing protocol was (1) add cement, fine aggregate,
and water at the same time and mix for 60 seconds at
the first speed, then (2) mix for 60 seconds at the
second speed. For concrete mixtures, a twin-shaft
mixer was used. The mixing protocol was (1) mix dry
mix binder and aggregate for 20 seconds at low speed
(20 srpm), then (2) add water, retarder, and air entrainer
at high speed mixing (40 rpm) for 180 seconds. The
mixed specimens were demolded after one day and
cured in a water bath at 20 ± 2 oC until removal at
required age.
Tests methodsTo evaluate the fresh state mortar properties, workability
was measured using a mini-slump test following the KS F
2476 standard (similar to ASTM C143 [19] but with
smaller cone dimension of 50 mm in the upper circle, a
diameter of 100 mm in the lower circle, and a 150 mm
height). The fresh state tests were conducted three
times for repeatability, and the results were obtained by
averaging the measured values. For hardened mortar
properties, compressive strength was measured on a
50 mm cubic specimen using 3000 kN UTM following
ASTM C109 [20] at given ages. Each measurement
was performed three times, and the end results have
averaged values.
The fresh state properties of concrete, slump and air
content were measured following ASTM C143 and
C231 [21] methods, respectively. All fresh state tests
were conducted with three different samples obtained
from different areas in the mixed concrete. The
mechanical properties of the hardened concrete were
determined on specimens cast according to ASTM C39
[22] protocols. Compressive strength, split tensile
strength, and elastic modulus were measured following
ASTM C39, C496 [23], and C469 [24], respectively, at
the scheduled designated curing times. For the flexural
strength test, a specimen beam was cast with a length
of 400 mm × 100 mm (height) × 100 mm (depth), and
the test was conducted following ASTM C78 [25]
according to its prefixed curing times. For autogenous
shrinkage, the test method suggested by the Japan
Concrete Institute [26] was utilized. The deformation
of specimens was measured with an embedded gauge
as shown in Fig. 2. The tests measuring the concrete’s
mechanical properties were conducted with three
specimens, and the autogenous shrinkage test was
performed with two specimens to assure accuracy of
the results, which were averaged.
To evaluate the durability of the concrete with
various additives, freeze-thaw tests and carbonation
resistances were measured. Freeze-thaw tests were
conducted using another 400 mm × 100 mm × 100 mm
Table 5. Physical and chemical properties of binders.
Binder*L.O.I (%)
Density (g/cm3)
Blaine (cm2/g)
Chemical compositions (%)**
SiO2 Al2O3 Fe2O3 CaO MgO SO3
“S” RSC 2.3 2.91 5,854 11.00 11.30 2.66 49.90 1.70 12.10
“U” RSC 2.8 2.93 4,697 10.40 17.20 1.40 54.50 1.40 11.40
CAC 1.2 2.95 5,600 19.40 26.60 1.32 43.00 6.41 2.21
Acement 2.4 2.85 5,250 22.70 20.00 1.01 38.90 4.72 8.20
*“S” RSC: rapid setting cement from “S” company, “U” RSC: rapid setting cement from “U” company.**obtained from XRF.
Table 6. Physical properties of aggregates.
AggregateFineness modulus*
Density (g/cm3)
Absorption rate (%)
Fine aggregate 2.98 2.62 2.11
25 mm coarse aggregate
7.13 2.68 1.37
*Fineness modulus was measured using the standard sieve set ofASTM C136 [18].
Table 7. Physical properties of chemical admixtures.
Type Base Phase ColorDensity (g/cm3)
pH
Water reducer
Naphthalene sulfonic acid
Powder Brown 1.5 −*
Retarder Citric acidPowder
(Granular)White −* 2-3**
*not provided by manufacturer.**measured in suspension phase.
Fig. 2. Schematic test setting for autogenous shrinkage.
Evaluation of the feasibility of using calcium aluminate composite (CAC) and Acement as additives for regulated set cement 1159
beam specimen following ASTM C666 [27] after 14
days of curing. The accelerated carbonation test [28]
was performed on the same size specimens, which
were cured in a water bath for 28 days and stored at a
20 ± 2 oC temperature, and 60 ± 5% relative humidity for
56 days in a CO2 chamber with 5% CO2 concentration.
After preparation, the specimens were stored in the CO2
chamber until testing at 1, 4, 8, and 13 weeks. To test, the
specimens were cut perpendicular to the longitudinal
direction of the beam and a 1% phenolphthalein
suspension was applied on the cross section of the
specimens at 60 mm from the edge. The carbonation
depth was obtained as the average of 10 points on two
surfaces.
Results and Discussion
Mortar propertiesFigs. 3 and 4 show the properties of fresh state
mortar depending on different replacement ratios of
rapid setting additives. As shown in Fig. 3, all mixtures
with rapid setting additives showed higher discharging
temperature than plain RSC, and the discharging
temperature increased with the increasing replacement
ratio of rapid setting additives. It was determined that
the CAC and Acement with a main component of
C12A7 have higher reactivity than plain rapid setting
cement (RSC). The mini-slump of all mixtures satisfied
the target slump range (see Fig. 4). From this result, it
can be stated that the fresh state mortar with rapid
setting additives possesses sufficient workability while
retaining fast reactivity.
The effect of replacement ratios of CAC on
compressive strength of the mortars depending on ages
is shown in Fig. 5. Generally, with a CAC replacement
ratio of 10%, higher compressive strength values were
shown at the end of the three-day curing process. After
three days of curing, compressive strength values
comparable to the plain mixture were obtained. C12A7
is a main component of CAC and produces ettringite as
a result of the reaction with CaSO4 (see Equation (2))
This fast formation of ettringite is considered the
reason for higher compressive strength at early age.
(before three days of curing is completed), which is
higher than that of the RSC plain mixture. On the
other hand, when the mixture contains over 20% CAC,
compressive strength values were lower than that of the
plain mixture regardless of age. It can be stated that the
amount of C12A7, a main component of CAC, is not
enough to consume all gypsum for ettringite, so C3AH6
Fig. 3. Effect of replacement of rapid setting additives ontemperature after mixing process.
Fig. 4. Effect of replacement of rapid setting additives on mini-slump.
Fig. 5. Effect of replacement ratio of CAC on compressivestrength depending on curing time.
Fig. 6. Effect of replacement ratio of Acement on compressivestrength depending on curing time.
1160 Ja-Sul Koo, Seung-Yeup Yoo, Jin-Man Kim, Sun-Mi Choi, Sang-Yoon Oh and Dongyeop Han
of the low-strength trisoctahedral stable phase was
produced after forming sub-stable phases of C2AH8,
C4AH19, and C4AH13.
The effect of the replacement ratio of Acement on
compressive strength of mortar depending on age is
shown in Fig. 6. In this case, all the mixtures replacing
Acement showed higher compressive strength than the
plain mixture after only three hours. It is thought that,
similar to the CAC results, ettringite formation contributes
to the fast strength development within the three-hour
curing process. Since after three hours, all mixtures
showed a compressive strength lower than the plain
mixtures, it can be considered that the amount of
hydration product with C3AH6 is less than that of the
CAC mixtures because of the lesser amount of CAC in
Acement.
Consequently, based on the results of these
experiments, it is possible to use CAC and Acement as
rapid setting additives for RSC, with the optimum
replacement ratios being 10% for CAC and 20% for
Acement to RSC weight.
Concrete propertiesFigs. 7, 8, and 9 show the fresh state properties of
concrete depending on different binder conditions. In
Fig. 7, all concrete mixtures with rapid setting additives
show higher post-mix temperatures than Plain RSC
mixtures, regardless of the RSC brands. CAC and
Acement showed higher reactivity and better hydration
than Plain RSCs. Moreover, the workability of the
concrete mixtures satisfied the target range with the
appropriate mix design (see Fig. 8). With 10% CAC
content and 20% Acement content, workability was
decreased regardless of the types of RSCs. This was
due to slump loss caused by the fast reaction of CAC
and Acement in RSC binders. Regarding air content of
rapid setting concrete, all mixtures showed favorable
results within the target range (see Fig. 9).
(1) Compressive strength: Fig. 10 shows compressive
strength test results depending on various binder
conditions. Generally, the compressive strength of the
mixtures with 10% CAC and 20% Acement was higher
than that of the plain mixtures from “S” and “U”
companies. This is attributed to the increased reactivity
due to replacing CAC and Acement as well as mortar
experiment results.
(2) Tensile strength, flexural strength, and elastic
modulus: The mechanical performance test results for
tensile strength, flexural strength, and elastic modulus
are shown in Figs. 11-13, respectively. For all three
Fig. 7. Effect of various binders on temperature after the mixingprocess of the fresh state concrete.
Fig. 8. Effect of various binders on slump of the fresh stateconcrete.
Fig. 9. Effect of various binders on air content of the fresh stateconcrete.
Fig. 10. Effect of various binders on compressive strength of theconcrete mixtures.
Evaluation of the feasibility of using calcium aluminate composite (CAC) and Acement as additives for regulated set cement 1161
mechanical tests, the concrete mixtures with CAC and
Acement showed slightly improved performance. This
can be related to compressive strength results.
(3) Autogenous shrinkage deformation: Figs. 14-15
show deformation of concrete specimens within 150
minutes (2.5 hrs) and within 14 days, respectively.
Based on the figures, the mixture with 10% CAC
showed high expansion at an early age, which means
the expansion was similar to plain mixture after 90
minutes (see Fig. 15). This is considered a result of the
fast formation of ettringite by the reaction of CAC
following transformation to monosulfate because of
insufficient gypsum for further ettringite formation.
However, in the case of the mixture with 20% Acement,
the expansion was higher than that shown in other
mixtures and this expansion continued to the end of the
testing period because of the additional gypsum from
the process of Acement production from CAC.
(4) Freeze-thaw resistivity: Figs. 16-17 show the relative
dynamic modulus and weight change, respectively, after
Fig. 11. Effect of various binders on tensile strength of differentconcrete mixture classifications.
Fig. 12. Effect of various binders on flexural strength of differentconcrete mixture classifications.
Fig. 13. Effect of various binders on elastic modulus of differentconcrete mixture classifications.
Fig. 14. Effect of various binders based on “S” RSC onautogenous shrinkage (within 150 minutes).
Fig. 15. Effect of various binders based on “S” RSC onautogenous shrinkage (within 14 days).
Fig. 16. Effect of various binders on relative dynamic modulusafter freeze-thaw cycles.
1162 Ja-Sul Koo, Seung-Yeup Yoo, Jin-Man Kim, Sun-Mi Choi, Sang-Yoon Oh and Dongyeop Han
the freeze-thawing test. Among the two plain commercial
RSC products, “U” company’s RSC showed less
degradation of relative dynamic modulus and weight
change than “S” company’s RSC. Furthermore, as rapid
setting additives of CAC or Acement were replaced, the
degradation of the relative dynamic modulus and weight
change increased regardless of the RSC brands.
Accelerated carbonation depth: After the accelerated
carbonation test, the carbonation depth of the specimens
was graphed in Fig. 18. In respect to carbonation depth,
the RSC from “U” company showed faster carbonation
(deeper carbonation depth) than the RSC from “S”
company. Replacing CAC or Acement in RSC increased
carbonation depth regardless of the RSC brands.
Conclusions
This research analyzed the properties and compressive
strength of CAC obtained from rapid air cooled molten
steel slag and Acement manufactured from crushed
CAC with gypsum and other additives. The results from
these tests were compared to tests conducted on two
types of plain cement from two different companies.
Properties of mortar and concrete prepared with CAC or
Acement binders based on a commercially available
CSA-based rapid setting cement were measured. Test
results led to the following conclusions:
The results of the experiment for mortar properties:
Experiments conducted to determine the replacement
ratios of CAC and Acement on properties of mortar
showed that as the replacement of CAC increased, mortar
compressive strength decreased because of a lack of
gypsum to produce sufficient amounts of ettringite.
However, Acement with added gypsum in a CAC powder
additive increased compressive strength. Gypsum was the
key factor contributing to the compressive strength
increase between CAC and Acement. Based on the mortar
experiment-Acement, as the rapid setting additive for
RSC, showed better performance than CAC within 10%
of replacement ratio. The RSC mixture that replaced
CAC also showed acceptable performance.
The results of experiment for concrete properties.
When 10% CAC or 20% Acement content replaced
RSC, the mechanical properties of compressive strength,
tensile strength, flexural strength, and elastic modulus
were improved. In spite of these improved mechanical
properties, rapid setting additives of CAC and Acement
decreased durability in freeze-thaw and carbonation
resistivity tests. Therefore, further research should be
performed for improving durability of RSC with CAC
or Acement.
Acknowledgements
This work was supported by the research grant of the
Kongju National University in 2015.
References
1. P. Mehta, Concr. Int. 31 (2009) 45-48.2. D. Fowler, in Second International Conference on
Sustainable Construction Materials and Technologies, June2010, edited by T. Naik, F Canpolat, P Claisse, and EGanjian (Coventry University and The University ofWisconsin Milwaukee Center for Byproducts Utilization,2010).
3. P. Aïtcin and S. Mindess, Sustainability of concrete, NewYork, Spon Press (2011).
4. K. I. and S. Association, Steel-making statistic data.5. C. Shi, J. Mater. Civ. Eng. 16[230] (2004) 230-236.6. J.-M. Kim, S.-H. Cho, S.-Y. Oh, and E.-G. Kwak, J. Korea
Concr. Inst. 19[39] (2007) 39-457. J. Manso and M. Losañez, J. Mater. Civ. Eng. 17[513]
(2005) 513-518.8. J. Setién, D. Hernández, and J. González, Constr. Build.
Mater. 23[1788](2009)1788-1794.9. T. I. and S. I. of J. Research committee of basic and
applications of steel slag, Reducing amount of occurenceand recycling of steel slag: The final report from theresearch committee of basic and applications of steel slag,Tokyo, Japan (1997).
10. S. Takayama, T. Idemitsu, N. Aida, M. Sugi, and H.Tokuhara, J. Japan Soc. Civ. Eng. 544 [177] (1996) 177-186.
11. K. Lee, J. Koo, J. Kim, and S. Oh, in Proceesings of ISWAWorld Congress, 2013 (International Solid Waste
Fig. 17. Effect of various binders on weight change after freeze-thaw cycles.
Fig. 18. Effect of various binders on carbonation depth dependingon the curing time.
Evaluation of the feasibility of using calcium aluminate composite (CAC) and Acement as additives for regulated set cement 1163
Association, 2013).12. P. Barnes and J. Bensted, Structure and performance of
cements, New York, Spon Press (2002).13. S. Ghosh, Cement and concrete science & technology, New
Delhi, India, ABI Books Privte Limited (1991).14. M. C. G. Juenger, F. Winnefeld, J. L. Provis, and J. H.
Ideker, Cem. Concr. Res. 41[1232] (2011)1232-1243.15. D. Damidot and A. Rettel, in Proceedings of the 11th
International Congress on the Chemistry of Cement, May2013, edited by G. Grieve, and G. Owens (The Cement andConcrete Institute of South Africa, 2013) 1855.
16. T. Kong, Enhanced durability performance of regulated setcement concrete, Ph.D. Dissertation, Konkuk University,Seoul, South Korea (2005).
17. F. Lea, Lea’s Chemistry of Cement and Concrete,Burlington, MA, Elsevier Ltd. (2003).
18. ASTM International, ASTM C136, Standard Test Methodfor Sieve Analysis of Fine and Coarse Aggregate, WestConshohocken, PA, ASTM International (2006).
19. ASTM International, ASTM C143, Standard Test Methodfor Slump of Hydraulic-Cement Concrete, WestConshohocken, PA, ASTM International (2012).
20. ASTM International, ASTM C109, Standard Test Methodfor Compressive Strength of Hydraulic CementMortars ( Using 2-in or [50-mm ] Cube Specimens), WestConshohocken, PA, ASTM International (2013).
21. ASTM International, ASTM C231, Standard Test Methodfor Air Content of Freshly Mixed Concrete by the PressureMethod, West Conshohocken, PA, ASTM International(2010).
22. ASTM International, ASTM C39, Standard Test Methodfor Compressive Strength of Cylindrical ConcreteSpecimens, West Conshohocken, PA, ASTM International(2012).
23. ASTM International, ASTM C496, Standard Test Methodfor Splitting Tensile Strength of Cylindrical ConcreteSpecimens, West Conshohocken, PA, ASTM International(2011).
24. ASTM International, ASTM C469, Standard Test Methodfor Static Modulus of Elasticity and Poisson’ s Ratio ofConcrete in Compression, West Conshohocken, PA, ASTMInternational (2010).
25. ASTM International, ASTM C78, Standard Test Methodfor Flexural Strength of Concrete (Using Simple Beamwith Third-Point Loading), West Conshohocken, PA,ASTM International (2010).
26. E. Tazawa, Autogenous shrinkage of concrete, New York,E & FN SPON (1999).
27. ASTM International, ASTM C666, Standard Test Methodfor Resistance of Concrete to Rapid Freezing and Thawing,West Conshohocken, PA, ASTM International (2008).
28. C. Ati , Constr. Build. Mater. 17[147] (2003) 147-152.sç